Flooding of Piazza San Marco (Venice): Physical model tests to evaluate the overtopping discharge

This paper aims at evaluating the wave overtopping discharge over the pavement of "Piazza S. Marco" (Venice) in order to select the best option to mitigate the risk of flooding of the Piazza and to protect the monuments and historic buildings, e.g., the "Basilica S. Marco". In fact, the MO.S.E. (MOdulo Sperimentale Elettromeccanico) system is designed to keep the water level below a certain value, for the safety of the lagoon, but it does not guarantee the defence of the Piazza, where flooding is still possible, being its pavement locally much lower than the maximum expected water level. To completely defend the Piazza, specific additional works are planned to prevent the back-flow through the natural drainage system (now the primary pathway) or by filtration or by overtopping. This paper investigates on the overtopping mechanism, under conditions compatible with a fully operational MO.S.E. system, through 2-D experiments. The pavement of the Piazza is gently sloping towards the masonry quay which, in some parts is formed by 5 descending steps, and in some other parts, is just a vertical wall. Close to the "Marciana" Library, a critical part is present, with a slightly lower crest freeboard. In total, three cross-sections were examined in the 36 m long wave flume of the Padova University. The test programme includes 10 irregular wave attacks and three different water levels. The test results differ considerably from the results of the available formulas, since the investigated cross-sections by far exceed their range of applicability. The presence of the steps affects only the reflection coefficient rather than the overtopping discharges. In general, if the waves incident to the Piazza are higher than 40 cm, which is a possible scenario, some other adaptation works must be considered, such as the pavement rise, temporary barriers or the reduction of the waves impacting the quay through, for instance, floating breakwaters

Variáveis morfológicas na produção de mudas de Allophylus edulis (St Hil.) Radl. (vacum) em diferentes substratos.

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Produção de mudas de Schinus terebinthifolius Raddi (aroeira-vermelha) em diferentes substratos.

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Características físicas de substratos para produção de mudas de Allophylus edulis (ST Hil.) Radl. e Schinus terebinthifolius.

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Efficient second harmonic generation from thin films of V-shaped benzo[b]thiophene based molecules

We have designed an original approach for efficient Second Harmonic Generation of tailored V-shape benzo[b]thiophene molecular systems enabling versatile and flexible one-step, dry and technologically friendly thin film processing. The designed moieties show χ(2) values at least as high as the reference LiNbO3 single crystal, without poling processing and matching the constrains of integrated optical configuration for nonlinear optical devices. This may open the way to a new class of organic materials exploitable for photonic applications

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ISSN: 2239-273

Avaliação de indicadores associados à conservação dos recursos hídricos em distintos sistemas de uso da terra para valoração de serviços ambientais.

O objetivo do trabalho é avaliar e comparar indicadores ambientais associados aos recursos hídricos entre distintos sistemas de uso da terra, desde campo e oresta natural passando por sistemas agrosilvopastoril (uma modalidade de sistema agro orestal) e silvicultural até o outro extremo, em monocultura de plantas anuais. A quanti cação e a modelagem desta relação subsidiarão os estudos de valoração dos serviços ambientais prestados nos diferentes usos da terra. ABSTRACT - There is an association between the type and intensity of land use and the quantity and quality of environmental services generated but there are knowledge gaps of the quanti cation of environmental indicators. The objective is to evaluate and compare environmental indicators associated to water resources between different land uses systems from natural eld and forest, silvopastoral and silviculture system to annual crops. The study plots are located in Ponta Grossa, Tibagi River basin, Atlantic Forest biome, Brazil. The quanti cation and modeling these studies will support the valuation of environmental services and hydrological processes in different land uses

Visible-Light Assisted Covalent Surface Functionalization of Reduced Graphene Oxide Nanosheets with Arylazo Sulfones

We present an environmentally benign methodology for the covalent functionalization (arylation) of reduced graphene oxide (rGO) nanosheets with arylazo sulfones. A variety of tagged aryl units were conveniently accommodated at the rGO surface via visible-light irradiation of suspensions of carbon nanostructured materials in aqueous media. Mild reaction conditions, absence of photosensitizers, functional group tolerance and high atomic fractions (XPS analysis) represent some of the salient features characterizing the present methodology. Control experiments for the mechanistic elucidation (Raman analysis) and chemical nanomanipulation of the tagged rGO surfaces are also reported

Rubbing induced reversible fluorescence switching in thiophene-based organic semiconductor films by mechanical amorphisation

Here, we applied rubbing on thiophene-basedorganic semiconductor thin films to induce a reversible mechanical amorphisation. Amorphisation is associated with fluorescence switching, which is regulated by the polymorphic nature of the film. Thermal annealing of rubbed films produces an opposite effect with respect to rubbing, inducing film crystallization. Notably, thermal crystallisation starts at a low temperature but generates the polymorph stable at a high temperature in the bulk. The mechanism of mechanical transformation is explained considering the mechanical properties of the material and demonstrated through combined X-ray diffraction, atomic force microscopy and photoluminescence at confocal microscopy. This journal i